1. Field of the Invention
The present invention relates to liquid-crystalline compounds having α,β-unsaturated carbonyl (propenoyl) and their polymers, to use of the polymers, and to a method for producing the compounds. The polymers may be usable for optically-anisotropic materials and for liquid-crystal display devices.
2. Description of the Related Art
Polymerizable liquid-crystalline compounds are used these days for optically-anisotropic materials for polarizers, retarders, etc. This is because the compounds are optically anisotropic while they are in liquid-crystalline condition, and their orientation is fixed through polymerization. The necessary optical characteristics of optically-anisotropic materials vary depending on the object of the shaped articles, and compounds of which the characteristics could meet the object are needed. In using them, in general, the compounds are polymerized into their polymers, and the polymers are molded. Of the compounds for that object, the characteristics of the polymers are also important in addition to the above-mentioned anisotropy thereof. The characteristics include the polymerization rate of the compounds, and the transparency, the mechanical strength, the coatability, the solubility, the degree of crystallinity, the degree of shrinkage, the water permeability, the water absorption, the melting point, the glass transition point, the clearing point and the chemical resistance of the polymers.
Acrylates are highly reactive for polymerization and their polymers are highly transparent, and therefore they are used for the object as above (for example, see patent reference 1, patent reference 2 and patent reference 3). However, acrylates could not fully satisfy the characteristics of liquid crystallinity, compatibility with other compounds, and optical anisotropy. In addition, all acrylate polymers are not always good in point of the transparency, the mechanical strength, the coatability, the solubility, the degree of crystallinity, the degree of shrinkage, the water permeability, the water absorption, the melting point, the glass transition point, the clearing point and the chemical resistance thereof. Given that situation, it is an urgent theme in the art to develop compounds, of which the uppermost temperature of the liquid crystalline phase is high or the temperature range of the liquid crystalline phase is broad and which have good compatibility with others, and to develop their polymers that are good in point of the mechanical strength, the coatability, the solubility, the degree of shrinkage, the water permeability, the water absorption, the melting point, the glass transition point, the clearing point and the chemical resistance thereof.
The related art of α,β-unsaturated carbonyl-having liquid-crystalline compounds is, for example, in patent reference 4 and patent reference 5.    Patent Reference 1: JP-A 7-17910/1995    Patent Reference 2: JP-A 8-3111/1996 (U.S. Pat. No. 5,863,457A)    Patent Reference 3: JP-A 9-316032/1997    Patent Reference 4: German Patent Laid-Open No. 19919153 (U.S. Pat. No. 6,440,328B1)    Patent Reference 5: Pamphlet of International Patent Laid-Open No. 97/23580 (U.S. Pat. No. 5,798,057A)